Air vanes of low hinge moments



Feb. 22, 1966 w, DAHM 3,236,182

AIR VANES OF LOW HINGE MOMENTS Filed June 5, 1964 -|o.|s FIG 4 Werner K. DO FIG 5 IVENTOR.

BY Zzf United States Patent 3,236,182 AIR VANES OF LOW HINGE MOMENTS Werner K. Dahm, Huntsville, Ala., assignor to the United States of America as represented by the Secretary of the Army Filed June 3, 1964, Ser. No. 372,436 Claims. '(Cl. 102-50) (Granted under Title 35, US. Code (1952), sec. 266) The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.

This invention relates to air vanes that are designed with low hinge moments for the guidance of high speed airborne missiles.

In missiles, the weight of each component and the space occupied by each component is very important in that the weight and space of the missile must be conserved. Therefore, air vanes of low hinge moments are needed so that the actuator for the air vanes may be made as small and light as possible. Also, air vanes of low hinge moments are adapted for more rapid and stable operation since they require less force for actuation thereof.

With this in mind, it is an object of this invention to provide air vanes that are designed for use on airborne missiles that fly at supersonic speeds and above.

Another object of this invention is to make the plan form and profile of each air vane, such that the shifts of the center of pressure with changing Mach number inherent in the planform and the profile approximately compensate each other.

A further object of this invention is to maintain the center of pressure of the air vane close to the vane hinge axis.

Still another object of this invention is to provide an air 'vane with high lifting efficiency, that is, an air vane with a thick trailing edge and a reduced vane area.

In accordance with this invention, air vanes are provided that are generally wedge shaped in profile and generally rectangular in planform. The air vanes are designed with a thick trailing edge for high lifting efiic-iency and are so proportioned in profile and planform that the shifts of the center of pressure with changing Mach number inherent in the planform and the profile approximately cancel each other so that each air vane may be hinged about an axis that is slightly forward of and near the center of pressure of the air vane. With this relationship of the center of pressure to the hinge axis, the force required to actuate each air vane is reduced to a minimum.

In the accompanying drawings, forming a part of this specification, and in which like numerals are employed to designate corresponding parts throughout the same:

FIGURE 1 is a perspective view illustrating an air vane mounted on a missile body according to one embodiment of this invention,

FIGURE '2 is a side elevational view of the air vane illustrated in FIGURE 1,

FIGURE 3 is an end elevational view of the air vane illustrated in FIGURE 1,

FIGURE 4 is a side elevational view of an air vane according to a second embodiment of this invention, and

FIGURE 5 is an end elevational view of the air vane illustrated in FIGURE 4.

Referring now to FIGURES 1 through 3, there is shown an air vane 1 that has a generally rectangular planform 3 as illustrated in FIGURE 2. Air vane 1 has a ratio in units of length to width of 0.906 to 1 and has a hinge axis 5 that is located 0.375 unit from forward edge 7.

Air vane 1 is double wedge shaped in profile as illustrated in FIGURE 3 and has a forward Wedge portion 9 that has an apex angle of 21.85 and a rear wedge portion 11 that has an apex angle, half of which is 5.46". The trailing edge 13 of the air vane is relatively thick and spans 0.25 unit.

Shaft 15 hingedly mounts air vane 1 on the outer periphery of body portion 17, and conventional actuating means may be used to actuate shaft 15 and in turn ai-r vane 1 through an arc of control as desired.

In operation, air vane 1 has been shaped and proportioned for guiding a body that travels at moderately high supersonic speeds. In this range of speeds, the relationship of hinge axis to center of pressure of the air vane remains substantially constant due to the relationship of the planform to the profile. That is, the broken wedge profile has a forward shifting center of pressure with increasing Mach number, while the rectangular planform has a rear-Ward shifting trend, with both eifects compensating each other in the range of operation of this design.

Turning now to the second embodiment of the invention as illustrated in FIGURES 4 and 5, an air vane 21 has a generally rectangular planform 23 as illustrated in FIGURE 4. Air vane 21 has a length to width ratio of 1 to 1 and has a hinge axis 24 that is half way between forward edge 25 and trailing edge 27. A shaft 29 is adapted to rotatably mount air vane 21 relative to .a missile body portion, and a conventional actuating means may be used to actuate air vane 21 through an arc of control by way of shaft 29.

Air vane 21 has a profile 31 in the form of a simple wedge as illustrated in FIGURE 5, and trailing edge 27 of the air vane in relatively thick and spans approximately 0.15 unit. By using a thick trailing edge, the vane area needed for proper control is greatly reduced.

In operation, at speeds from high supersonic speed to hypersonic speeds, the change in the center of pressure due to the rectangular planform and the simple Wedge profile is substantially invariant, and the center of pressure accordingly remains slightly rearward of and near the hinge axis of the air vane.

It is to be understood that the forms of my invention, herewith shown and described, are to be taken as preferred examples of the same, and that various changes may be resorted to, without departing from the spirit of my invention, or the scope of the subjoined claims.

I claim:

-1. An air vane for mounting on the outer periphery of a missile body for guidance thereof; said air vane being rectangular in pl-anform, wedge shaped in profile with a relatively thick .and flat trailing edge; and said air vane having a hinge axis located slightly forward of and near the center of pressure of the air vane so as to minimize the effects of air flow thereon and thereby adapt the air vane to be actuated with .a minimum amount of force about said hinge axis.

2. An air vane as set forth in claim 1, wherein the profile is double wedge shaped.

3. An air vane as set forth in claim 1, wherein the profile is a simple wedge shape.

4. An air vane as set forth in claim 1, wherein the planform of the air vane has a length to width ratio of approximately one to one, the profile of the air vane is triangular in shape with a trailing edge that spans approximately 0.15 unit, and the hinge axis is located approximately half Way along the length of the air vane.

5. An air vane as set forth in claim "1, wherein the planform of the air vane has a length to width ratio of approximately 0.906 to 1, the profile of the air vane is double wedge shaped with a forward wedge portion that has an apex angle of approximately 21.85" and a rear Wedge portion that has an apex angle, half of which is approximately 5 .46.

(References on following page) 3 4 References Cited by the Examiner FOREIGN PATENTS UNITED STATES PATENTS 857,540 12/1960 Great Britain.

2,414 9 v 1 1947 Rous 102 50 BENJAMIN A. BORCHELT, Primary Examiner. 3,113,517 12/1963 Kelley et a1. 10250 5 V. R. PENDEGRASS, Assistant Examiner. 

1. AN AIR VANE FOR MOUNTING ON THE OUTER PERIPHERY OF A MISSILE BODY FOR GUIDANCE THEREOF; SAID AIR VANE BEING RECTANGULAR IN PLANFORM, WEDGE SHAPED IN PROFILE WITH A RELATIVELY THICK AND FLAT TRAILING EDGE; AND SAID AIR VANE HAVING A HINGE AXIS LOCATED SLIGHTLY FORWARD OF AND NEAR THE CENTER OF PRESSURE OF THE AIR VANES SO AS TO MINIMIZE THE EFFECTS OF AIR FLOW THEREON AND THEREBY ADAPT THE AIR VANE TO BE ACTUATED WITH A MINIMUM AMOUNT OF FORCE ABOUT SAID HINGE AXIS. 